from __future__ import annotations

import argparse
from pathlib import Path

from PIL import Image


ROOT = Path(__file__).resolve().parents[1]
DEFAULT_SOURCE_DIR = ROOT / "tmp" / "imagegen"
OUTPUT_ROOT = ROOT / "src" / "assets" / "images" / "ui" / "equipment-icons"


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(
        description="Build centered 128px and 32px equipment icons from transparent source art."
    )
    parser.add_argument("ids", nargs="+", help="Equipment ids whose <id>-alpha.png source should be built.")
    parser.add_argument("--source-dir", type=Path, default=DEFAULT_SOURCE_DIR)
    return parser.parse_args()


def fit_icon(source: Image.Image, size: int) -> Image.Image:
    rgba = source.convert("RGBA")
    bounds = rgba.getchannel("A").getbbox()
    if bounds is None:
        raise ValueError("source image has no visible pixels")

    cropped = rgba.crop(bounds)
    inner_size = max(1, round(size * 0.88))
    scale = min(inner_size / cropped.width, inner_size / cropped.height)
    resized_size = (
        max(1, round(cropped.width * scale)),
        max(1, round(cropped.height * scale)),
    )
    resized = cropped.resize(resized_size, Image.Resampling.LANCZOS)
    canvas = Image.new("RGBA", (size, size), (0, 0, 0, 0))
    offset = ((size - resized.width) // 2, (size - resized.height) // 2)
    canvas.alpha_composite(resized, offset)
    return canvas


def main() -> None:
    args = parse_args()
    for size in (128, 32):
        (OUTPUT_ROOT / str(size)).mkdir(parents=True, exist_ok=True)

    for item_id in args.ids:
        source_path = args.source_dir / f"{item_id}-alpha.png"
        if not source_path.exists():
            raise FileNotFoundError(f"missing transparent source: {source_path}")

        with Image.open(source_path) as source:
            for size in (128, 32):
                output_path = OUTPUT_ROOT / str(size) / f"{item_id}.png"
                fit_icon(source, size).save(output_path, optimize=True)
                print(f"Wrote {output_path.relative_to(ROOT)}")


if __name__ == "__main__":
    main()